JPH10190398A - Piezoelectric component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mountable piezoelectric component with less fluctuation of characteristics for practically turning the number of components to three and improving productivity. SOLUTION: For this piezoelectric component, a piezoelectric resonance element 1 and a capacitive element are arranged in the state of being connected through a conductive adhesive material 7 inside a columnar case 3, input/output terminal electrodes 4 and 5 are formed at both end openings of the case 3 and the end face part of the piezoelectric resonance element 1 and the capacitive element and a ground terminal 6 connected to the common capacitor electrode of the capacitive element is formed on the mounting bottom surface of the case 3. In this case, the ground terminal 6 is integrally fixed to the mounting bottom surface of the case 3 and a through-hole 62 passed through the bottom surface thick part of the case 3 and filled with a conductor 8 connected to the capacitor element is provided on the fixing part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric component which can be surface-mounted on a printed circuit board and has a piezoelectric resonance element and a capacitance element.

[0002]

2. Description of the Related Art In a piezoelectric component having a piezoelectric resonance element and a capacitance element having two capacitance components, for example, the structure of the piezoelectric resonance element is such that vibration electrodes facing each other are formed on both main surfaces of a piezoelectric substrate, Of the vibrating electrodes form extraction electrodes extending to different ends. Further, in the capacitive element, two individual capacitance electrodes are formed on both ends of one main surface of the dielectric substrate, and a common capacitance electrode facing the two individual capacitance electrodes is formed substantially at the center of the other main surface. .

[0003] As a sealing structure of a piezoelectric component having such a piezoelectric resonance element and a capacitance element, a sealing structure of an exterior resin is known. This is because the piezoelectric resonance element and the capacitance element are disposed with a predetermined gap between the two elements, and lead terminals connected to the extraction electrodes at both ends of the piezoelectric resonance element and the individual capacitance electrodes of the capacitance element at the same time. After mounting, a ground terminal connected only to the common capacitance electrode of the capacitance element was attached, and then the piezoelectric resonance element and the capacitance element were covered with an exterior resin so as to form a vibration space.

Further, a piezoelectric component using a container body that can be divided into two parts has been known. This is, for example, the first
Using a case and a second case, for example, a lid,
The piezoelectric resonance element and the capacitance element were housed. Three terminal electrodes are formed in the first case, two of which are connected to the extraction electrode of the piezoelectric resonance element and the individual capacitance electrode of the capacitance element, and one terminal electrode is connected to the common capacitance electrode of the capacitance element. I was

[0005] In this case, the terminal electrode is formed so as to go around the first case, and is led out to the outside from the junction between the first case and the second case.

Further, there has been known a piezoelectric component in which a dielectric substrate of a capacitive element is also used as a first case. In this method, an individual capacitance electrode and a common capacitance electrode formed on a dielectric substrate of a capacitance element are extended to a mounting surface of the dielectric substrate, and a piezoelectric resonance element is arranged on the dielectric substrate and covered with a lid. Was.

Further, a piezoelectric component used for a cylindrical container has been known. This is because the input / output side terminal electrodes are provided on both sides of the outer periphery of a rectangular cylindrical outer container made of a dielectric material so that two capacitance components are achieved. The ground-side terminal electrode was attached.

[0008]

With the above-mentioned piezoelectric component sealed with an exterior resin, surface mounting has not been possible.

In the case of a piezoelectric component using a container body that can be divided into two parts, the cover needs to be larger in size than the piezoelectric resonance element and the capacitance element in order to cover the piezoelectric resonance element and the capacitance element with the cover. Yes, and furthermore, since it is necessary to stably seal the lid and the mounting substrate, this mounting substrate must be larger than the lid, and the overall shape becomes larger and the number of components is larger. Therefore, productivity was low.

The present invention has been devised in view of the above-mentioned problems, and has as its object to provide a surface-mountable piezoelectric component having a reduced number of components, improved productivity, and little change in characteristics. To provide.

[0011]

According to the present invention, there is provided a piezoelectric resonance element in which vibration electrodes are formed on both main surfaces of a piezoelectric substrate in a rectangular cylindrical case having both ends open, and at least one main surface of a dielectric substrate. Two individual capacitance electrodes, and a capacitance element having a common capacitance electrode opposite to each individual capacitance electrode formed on the other main surface, are respectively arranged, and both ends of the case are sealed at both ends. The piezoelectric component is formed by forming an input / output terminal electrode connected to the vibration electrode of the piezoelectric resonance element and the individual capacitance electrode of the capacitance element, and a ground terminal connected to the common capacitance electrode of the capacitance element on a mounting bottom surface of the case. . The ground terminal is integrally fixed to a mounting bottom surface of the case, and is electrically connected to a common capacitance electrode of the capacitance element through a conductor filled in a through hole provided in the case. Piezoelectric components.

[0012]

According to the present invention, a piezoelectric resonance element and a capacitance element are arranged in a rectangular cylindrical case in an integrated state. That is, since the piezoelectric resonance element and the capacitance element are bonded via the conductive adhesive, the electrical connection between them can be performed in a step different from the housing and disposing step, so that the connection reliability is improved.

Further, the terminal electrodes connected to the vibration electrodes of the piezoelectric resonance element and the individual capacitance electrodes of the capacitance element seal both ends of the case and become the terminal electrodes, so that the productivity and the reliability of the electrical connection of the terminal electrodes are improved. The performance is also improved.

Further, the common capacitance electrode of the capacitance element is connected to a ground terminal fixed to the mounting bottom surface of the case. That is, since the common capacitance electrode and the ground terminal are separate members, the capacitance component of the capacitance element does not change at all when the printed wiring board is soldered.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a piezoelectric resonance device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is an external perspective view of a piezoelectric resonance element according to the present invention, and FIG. 2 is a sectional view thereof.

In the figure, 1 is a piezoelectric resonance element, 2 is a capacitance element, 3 is a rectangular cylindrical case, 4 and 5 are terminal electrodes, and 6 is a ground terminal.

The piezoelectric resonance element 1 has a predetermined shape on a surface of a rectangular piezoelectric substrate 11 made of a piezoelectric ceramic material such as PZT or the like or a crystal material such as quartz, lithium tantalate, lithium niobate or lithium tetraborate. Is formed. In the figure, a piezoelectric substrate 11 such as PZT is shown.
The vibrating electrodes 12a and 12b facing each other are formed on both main surfaces. The extraction electrodes 13a and 13b are formed so that a predetermined voltage can be applied to the vibration electrodes 12a and 12b. For example, the extraction electrode 13a connected to the vibration electrode 12a extends to one end in the longitudinal direction of the piezoelectric substrate 11, and the extraction electrode 13b extends to the other end in the longitudinal direction of the piezoelectric substrate 11. I have. This vibrating electrode 12a,
12b and the extraction electrodes 13a and 13b are formed of, for example, a conductor film mainly composed of an Ag-based material.

The capacitive element 2 includes a rectangular dielectric substrate 21 made of a dielectric material such as BaTiO _3, and two individual capacitive electrodes 22 and 23 formed near both ends of one main surface.
And two individual capacitance electrodes 22 and 2 substantially at the center of the other main surface.
3 and a common capacitance electrode 24 formed so as to be opposed. Each of the capacitor electrodes 22, 23, and 24 is formed of, for example, a conductive film mainly containing an Ag-based material.

The piezoelectric resonance element 1 and the capacitance element 2 are formed so as to overlap with each other via the conductive adhesive 7. Specifically, the other main surface of the piezoelectric resonance element 1 and one main surface on which the individual capacitance electrodes 22 and 23 of the capacitive element 2 are formed are connected to each other through the conductive adhesive 7 near both ends in an overlapping manner. . Incidentally, the piezoelectric resonance element 1 and the capacitance element 2
Is simply referred to as a laminated element.

As a result, the extraction electrode 13b of the vibrating electrode 12b on the other main surface of the piezoelectric resonance element 1 is electrically connected to one of the individual capacitance electrodes 22, and a conductive adhesive is provided between the two elements 1, 2. A space corresponding to the thickness of the material 7 is formed.

The rectangular cylindrical case 3 is made of a heat-resistant resin such as a liquid crystal polymer, and is formed so that the accommodation through-holes 31 having a rectangular cross section slightly larger than the end surface shape of the laminated element are opened at both end surfaces of the case. Have been. The longitudinal dimension of the case 3 is set substantially equal to the longitudinal dimension of the piezoelectric substrate 11 and the dielectric substrate 21.

Further, tapered surfaces 32, 32 are formed in both rectangular opening portions of the accommodation through hole 31 of the case 3 so that the opening size is larger than that of the central portion. Further, a concave portion 33 for ensuring the vibration operation of the piezoelectric resonance element 1 is formed on the inner surface of the accommodation through hole 31 on the upper surface side of the case 3.

Further, a band-shaped ground terminal 6 made of, for example, white nickel is fixed to the bottom of the case 3. Specifically, a part of the ground terminal 6, in the figure, a part of the center part 61 is integrally fixed in the thick part of the bottom surface of the case 3 by resin molding. Case 3 with this integrated part
A through-hole 62 penetrating through the bottom thick portion of is formed. In addition, both ends of the ground terminal 6 fixed at the center of the band are formed along the width direction of the bottom surface of the case 3.
A part of the side surface is bent. As shown in the figure,
Since a part of the ground terminal 6 is fixed within the thick part of the bottom surface of the case 3, it is possible to integrally mold the resin. Therefore, there is no defective sealing, and the number of components can be reduced.

FIG. 3 is a bottom view showing a state before processing the ground terminal 6 and the case 3. The ground terminal 6 is formed of a lead frame body 63 and has a cylindrical central portion 6 of the ground terminal 6.
1 is integrally fixed on the bottom surface of the case 3. That is,
A cylindrical central portion 61 of the ground terminal 6 is a through hole 62.

The case 3 and the lead frame 6 shown in FIG.
3 is cut along the line XX in the figure,
The ground terminal 6 fixed to the case 3 is achieved by bending the ground terminal 6 along the side surface at the ridges on the bottom and side surfaces of the case 3.

Next, the structure of the terminal electrodes 4 and 5 and the electrical connection structure between the electrodes 4 and 5 and the ground terminal 6 will be described.

The terminal electrodes 4 and 5 are for sealing the openings at both ends of the case 3 and electrically connecting to the composite device arranged in the accommodation through hole 31. The terminal electrodes 4, 5 are composed of first conductor films 41, 51, second conductor films 42, 52, and surface plating layers 43, 53. The terminal electrode 4 is a lead electrode of the vibration electrode 12 a of the piezoelectric resonance element 1. 13a and the individual capacitance electrode 23 of the capacitance element 2 through the thickness of the conductive adhesive 7.
And the terminal electrode 5 is electrically connected to the extraction electrode 13b of the vibration electrode 12b of the piezoelectric resonance element 1 via the individual capacitance electrode 23 of the capacitance element 2 and the thickness of the conductive adhesive 7. I have.

The first conductor film 4 of the terminal electrodes 4 and 5
Reference numerals 1 and 51 are mainly formed by curing a conductive resin paste having low fluidity, and are mainly filled in a wedge-shaped space formed by a peripheral surface of an end portion of a composite element and a tapered surface 32 of a case. The second conductive films 42 and 52 are formed by curing a conductive resin paste, and are attached to the end of the case 3 including the end surface of the composite device. The surface plating layers 43 and 53 supplement the solder wettability of the second conductor films 42 and 52 and are made of, for example, Ni plating, Sn plating, solder plating, or the like.

Since the first conductor films 41 and 51 have relatively low fluidity, the through holes 31 for accommodating the composite element and the case are provided.
Hardly flows into the gap between the piezoelectric resonance element 1
And stable capacitance characteristics of the capacitive element 2 can be maintained.

Next, with respect to the ground terminal 6, as described above, the common capacitance electrode 24 on the other main surface of the capacitive element 2 is separated from the through hole 62 by the through hole 62 in the central portion 61 of the ground terminal 6.
Can be seen through. The through-hole 62 is filled with a conductive resin paste and filled with the cured conductor 8 to stably and electrically connect the ground terminal 6 and the common capacitance electrode 24 of the capacitance element 2. Can be completely sealed. In addition, you may form a plating layer on the surface of the conductor 8 and the earth terminal 6 as needed.

Next, the assembly of the piezoelectric component of the present invention will be briefly described.

First, the piezoelectric resonance element 1 on which the vibrating electrodes 12a and 12b and the extraction electrodes 13a and 13b are formed, the individual capacitance electrodes 22 and 23, the capacitance element 2 on which the common capacitance electrode 24 is formed, and the ground terminal 6 are fixed. Each cylindrical case 3 in which the through hole 62 is formed is prepared.

Next, a conductive resin adhesive 7 is applied to the ends of the individual electrodes 22 and 23 of the capacitive element 2 and superposed such that the other main surface of the piezoelectric resonance element 1 faces the surface. The conductive adhesive 7 is cured. Thus, the piezoelectric resonance element 1 and the capacitance element 2 become a composite element joined by the conductive adhesives 7, 7.

Next, the composite element is inserted and arranged in the accommodation through-hole 31 so as to form the piezoelectric resonance element 1 from the opening on one end face of the case 3 to the upper surface side of the case 3. At this time, since the tapered surface 32 is formed around the opening, the insertion operation can be performed very smoothly. Further, the piezoelectric resonance element 1 of the composite element arranged in the accommodation through-hole 31 has a vibration electrode 12a on one main surface arranged in the concave portion 33, thereby enabling stable operation.

Furthermore, in the capacitive element 2 of the composite element arranged in the accommodation through-hole 31, the common capacitance electrode 24 on the other main surface is located at the through-hole 62 in the thick portion on the bottom surface of the case 3. .

Next, the first conductive film 4 is filled in a wedge-shaped space between the composite element and the tapered surface 32 of the opening of the case 3 by filling and hardening a conductive paste having relatively low fluidity.
1 and 51 are formed. The first conductor films 41 and 51 are mainly provided at the ends of the composite device at the through holes 3 for housing of the case 3.
1 to seal the gap between the piezoelectric resonator element 1 and the extraction electrode 13a of the piezoelectric resonance element 1 and the end of the conductive adhesive 7 to the end.

Next, second conductive films 42 and 52 are formed on the end face of the composite element and both ends of the case 3 by applying and curing a conductive paste. The second conductor films 42, 5
Reference numeral 2 denotes a base layer for the terminal electrodes 4 and 5.

Next, in the through hole 61 on the bottom surface of the case 3,
The conductive film 8 is formed by filling and curing the conductive paste. As a result, electrical connection between the common capacitance electrode 24 of the capacitance element 2 and the ground terminal 6 fixed to the case 3 is achieved.

Finally, the second conductor film 4 to be the terminal electrode 4
Ni plating and solder plating are sequentially applied to the surface of the second conductor film 52, the surface of the second conductor film 52 to be the terminal electrode 5, and the exposed surfaces of the ground terminal 6 and the conductor 8, thereby forming surface plating layers 43 and 53. .

As described above, according to the present invention, the concave portion 33 and the gap between the piezoelectric resonance element 1 and the capacitive element 2 are formed in the center portion of the inner surface on the upper surface side of the accommodation through hole 31 of the rectangular cylindrical case 3. Since a vibration space is formed around the center of the piezoelectric resonance element 1, stable operation of the piezoelectric resonance element 1 can be ensured.

Further, tapered surfaces 32, 32 are formed so that the inner surfaces of the openings at both ends of the accommodation through hole 31 of the rectangular cylindrical insulating resin case 3 open outward. When the composite element composed of the piezoelectric resonance element 1 and the capacitive element 2 is inserted into one of the openings for housing arrangement in the accommodation through hole 31, the opening shape of the accommodation part is changed to the actual through hole 31 of the accommodation part.
Since the size of the piezoelectric resonance element is larger than the shape of the piezoelectric resonance element, the operation of inserting the piezoelectric resonance element becomes easy, and the insertion by an automatic machine becomes possible.

Since the conductor film 41 has a wedge-shaped opening formed by the end surface of the composite element and the tapered surface 32 made of a material having a relatively low fluidity, it is formed on one main surface of the piezoelectric resonance element. Since the conductor that adversely affects the operation does not flow into the other main surface of the capacitive element 2, the characteristics of the piezoelectric component do not change at all.

Since the first conductor films 41 and 51 can be formed separately from the second conductor films 42 and 52, for example,
For the conductor films 41 and 51, the optimum material can be appropriately used in consideration of the above-described inflow and for the second conductor films 42 and 52 in consideration of the plating adherence. The function of the electrodes 4 and 5 will be greatly improved.

Further, the dimension of the case 3 in the longitudinal direction can be the same as any one of the piezoelectric resonance element 1 and the capacitive element 2, and the dimension of the cross section of the case 2 is The thickness of the case 3 is added to the dimension in the cross-sectional direction of the composite element in which the piezoelectric element and the capacitive element 2 are joined, so that the entire piezoelectric component is very small.

Further, since the housing through-holes 31 of the case 3 can be arranged in a state where the piezoelectric resonance element 1 and the capacitor element 2 are laminated and integrated as a composite element, the electrical connection between them can be reliably performed. In addition, the operation of the insertion arrangement is greatly improved.

In a piezoelectric component having such a capacitive element 2, a ground terminal 6 as a third terminal is required. Since this ground terminal 6 is fixed to the cylindrical case 3 which is a separate member from the capacitance element 6 on which the common capacitance electrode 24 is formed, the ground terminal 6 is soldered to a printed wiring board using the ground terminal 6. However, the capacitance component of the capacitor 2 does not change.

Further, the connection between the ground terminal 6 and the common capacitance electrode 24 is made through a through hole 6 that penetrates a part of the ground terminal 6 through the thick portion on the bottom surface of the case 3 and communicates with the common capacitance electrode 24.
This is achieved by filling 2 with conductor 8. That is,
After the composite element is arranged at a predetermined position, the connection operation and the connection state can be maintained because the ground terminal is connected to the common capacitance electrode of the capacitance element 2, so that the reliability is greatly improved as a whole. become.

In the above-described piezoelectric component, the thickness of the piezoelectric resonance element 1 varies depending on the resonance frequency.
By controlling the thickness of the dielectric substrate on the side, the two elements 1, 2
The thickness of the composite element to which the piezoelectric element is attached can be made constant, and the case 3 may be shared by piezoelectric components having a plurality of characteristics.

[0050]

As described above, according to the present invention, there is provided a piezoelectric component having three terminals including a piezoelectric resonance element and a capacitance element having two capacitance components. And the capacitive element, the number of parts is very small, and the assembly productivity is improved. Further, the connection reliability between the ground terminal and the common capacitance electrode of the capacitance element is improved, and a piezoelectric component that can be surface-mounted with little change in characteristics is obtained.

Further, the piezoelectric resonance element and the capacitance element can be inserted into the case very easily, resulting in a piezoelectric resonance element with improved workability.

However, since the shape of the piezoelectric resonance element and the capacitance element can be made close to the shape of the case,
It becomes a small piezoelectric component.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a piezoelectric component of the present invention.

FIG. 2 is a sectional view of the piezoelectric component of the present invention.

FIG. 3 is a schematic view of a bottom surface side of a cylindrical case during a forming process of the present invention.

[Explanation of symbols]

 1 ... Piezoelectric resonance element 2 ... Capacitance element 21 ... Dielectric substrate 22, 23 ... Individual capacitance electrode 24 ... ···················································································· Terminal electrode 6 ·····. · Ground terminal 62 · · · · Through hole 8 · · · conductor

Claims (1)

[Claims] 1. A piezoelectric resonance element having vibration electrodes formed on both main surfaces of a piezoelectric substrate in a rectangular cylindrical case having both ends opened, and at least two individual capacitance electrodes on one main surface of a dielectric substrate.
Capacitors each having a common capacitance electrode formed in common with the individual capacitance electrodes on the other main surface are arranged, and both ends of the case are sealed, and the vibration of the piezoelectric resonance element is formed in the opening. An electrode and an input / output terminal electrode connected to the individual capacitance electrode of the capacitor, and a piezoelectric component formed on the mounting bottom surface of the case with a ground terminal connected to the common capacitance electrode of the capacitor, wherein the ground terminal is a case. A piezoelectric component, which is integrally fixed to a mounting bottom surface of the capacitor and electrically connected to a common capacitance electrode of the capacitance element via a conductor filled in a through hole provided in a case. .